Wear-resisting aluminum alloys



May 26, 1970 YATARO UNAI EI'AL 3,514,236

WEAR-RESISTING ALUMINUM ALLOYS Filed June 25, 1969 I HM 0.05- E 4 FIG. 2

0 I l 0.5 I v.0

m/sec FIG. 3

I I M United States Patent Int. Cl. C22c 21/02 us. or. 75-148 2 ClaimsABSTRACT OF THE DISCLOSURE A wear-resisting aluminum alloy containingsilicon from about 12% to about 25%, lead from about 3% to about tinfrom about 3% to about 20% and the balance consisting essentially ofaluminum.

This is a continuationdnpart of my prior application Ser. No. 495,109,filed Oct. 12, 1965 now abandoned.

This invention pertains to improvements in hyper-eutecticaluminum-silicon alloys containing optionally copper, magnesium, nickeland other ordinary contents, to which are added lead and tin, whichalloys are adapted primarily for use in cylinders and cylinder liners ofinternal combustion engines assembled with aluminum pistons.

In conventional internal combustion engines, pistons, cylinders andcylinder liners have been made of cast iron, and in part pistons made ofaluminum alloys have been used.

Recently hyper-eutectic aluminum alloys containing over 12% silicon arealso adapted for improving wearresistance. Today, the developments andstudies on substitution by aluminum alloys not only for pistons, but forcylinders and cylinder liners are being carried out in order to makeless in weight the engine as a whole.

u-Phase aluminum is precipitated (primary or eutectic) in aluminumalloys particularly aluminum-silicon alloys. This a-phase aluminum islow in wear-resistance, especially when two materials containing u-phasealuminum are mated, an abnormal wear of galling or scuffing will occur.That is why aluminum cylinders and cylinder liners are not used togetherwith aluminum pistons.

The alloys of the present invention contain 3 to 10% lead and 3 to 20%tin, added to 12% to 25% silicon hyper-eutectic aluminum-silicon alloyscomprising optionally small quantities of copper, magnesium, nickel andother ordinary contents. And these alloys are dotted with welllubricated lead particles and hard primary silicon, or formed withaluminum-eutectic matrix abundant in tin, or mixed with a combination ofthese lead and tin particles or materials providing thereby a highwear-resistance not only to conventional cast iron or chrome platedmaterials, but also even to aluminum-alloys.

The invention will become apparent from the following detaileddescription with reference to the accompanying drawings, wherein:

FIG. 1 is a microscopic section of a hyper-eutectic aluminum-siliconalloy containing lead and tin;

FIG. 2 represents the results of the metal-to-metal sliding wear testusing an ordinary aluminum-alloy, a cast 3,514,286 Patented May 26, 1970iron and an aluminum alloy of the present invention as one specimen andchrome-plated materials as the other mating specimens; and

FIG. 3 shows the results of the metal-t0-metal sliding wear test usingan ordinary aluminum alloy and an aluminum alloy of the presentinvention as one specimen and an ordinary aluminum as the other matingspecimens.

FIG. 1 shows the micro structure of aluminum-alloy containing 25%silicon, 2% copper, 1% magnesium, 3% tin, 10% lead and the balancesubstantially all aluminum. In aluminum-tin-eutectic matrix 4 bigeutectic silicon as crystal 2, tiny fine eutectic silicon 5, and minuteparticles of lead or lead and tin-eutectic 3a come out as a number ofblack dots.

FIGS. 2 and 3 respresent the results of comparative wear tests usingaluminum-alloys of the present invention or cast iron as one specimenand chrome-plated material as its other mating specimen and aluminumcastings containing 12% silicon, 1% magnesium, 1.2% nickel and thebalance all aluminum as its other mating specimen, respectively. Theresults of wear tests using specimens as follows: the aluminum-alloycontaining 20% silicon, 2% copper, 1% magnesium, 5% lead and the balancesubstantially all aluminum; the aluminum-alloy containing 20% silicon,2% copper, 1% magnesium, 20% tin, and the balance substantially allaluminum; the aluminumalloy containing 25 silicon, 2% copper, 1%magnesium, 3% tin, 10% lead and the balance substantially all aluminum;cast iron; and one of conventional aluminumalloysthat is-aluminum-alloycontaining 7% silicon, 0.2% copper, 3% magnesium, and the balancesubstantially all aluminum as each one specimen, are shown in therespective curves I, II, III, IV, and V, drawn as coordinates of thelongitudinal lines showing quantity of wear (mm?) and the lateral linesshowing friction velocity (m./s.). As shown in curve V, a conventionalaluminum-alloy is most remarkably poor in wear-resistance to chromeplated metal and aluminum-alloy containing neither lead nor tin,particularly in the case of the latter, scufling or galling occurs atthe point of about 0.2 m./sec. of wear-friction. Although the curves Iand II which contain lead or tin alone show high resistance to wear, thecurve III containing both lead and tin show the highest resistance towear in use in association with chrome-plated metal. Conventionalaluminum-alloy has very poor wear-resistance, and the new alloys showbetter results of wear-resistance than the conventional cast iron (curveIV) which has fairly high wear-resistance.

The aforesaid improvement in Wear-resistance of the alloy results fromthe good lubrication of the lead and tin materials in the alloys.Consequently, the aforesaid high resistance is not achieved by minoradditions of lead or tin. And best results cannot be secured by themajor additions, which will lead only to the increase of weight of itsproducts. For preferred contents of lead and tin, the former ranges from3 to 10% and the latter from 3 to 20%.

Hence, the new alloys require both lead and tin therein in the rangesstated. Small amounts of copper, magnesium and/or nickel may be presentin the alloy up to a total of about 7% so that one or more of thesematerials may be present within such range and excellent wear-resistanceis still obtained. In all alloys, the remainder is all aluminum subjectto the presence of normal incidentaliimpurities therein in very smallquantities.

The lubricating qualities of the alloys and wear resistance are believedto come from the characteristic of the tin and lead particles and thesilicon crystals in the aluminum-eutectic matrix 4 which is abundant intin.

Thus, it is believed that the objects of the invention have beenachieved.

What is claimed is:

1. A wear-resisting aluminum alloy which consists of 10 from 12 to 25%silicon, from 3 to 10% lead, from 3 to 20% tin; and the balanceessentially aluminum. 2. A modificationof an alloy as claimed in claim 14 which contains small quantities of at least one element of the groupconsisting of magnesium, copper and nickel, and the total amount ofadditional elements does not exceed 7%.

References Cited UNITED STATES PATENTS 2,026,542 11/1936 Kempfetal 751482,075,089 3/1937 Bonsack etal 75-143 RICHARD o. DEAN, Primary ExaminerUS. 01. X.R.

